IRS1 and type 2 diabetes mellitus: In addition, using data from 4752 Caucasians participating in the Whitehall-II study who had been genotyped for 33 IRS1 SNPs using the HumanCVD BeadChip [14,15] and with follow-up direct genotyping of IRS1 SNPs in the other study cohorts, we explored the potential association with the risk of T2D of SNPs within and flanking IRS1.